Calibration single point

Quantitation is performed by the single-point calibration technique. The calibration standard should be at a level similar to the expected residues and should be injected after every 3 samples throughout the sample batch. The mean response of the calibration standards which bracket the sample should be used for the residue calculation. 

Assay of active ingredients in a linctus using a single point calibration for each analyte... 

The validation also will give information about the extent and frequency of calibration that will be necessary during use. Having established the linearity of the calibration by the methods given below, the analyst may decide that a single-point calibration is sufficient for routine use in the laboratory. 

Concentration (% related substance) Figure 3.4. Single-point calibration. 

Case 3. Linearity demonstrated from 50% of the ICH reporting limit to 150% of the shelf life specification of a related substance, and a significant y-intercept is observed (Figure 3.8). Due to the significant -intercept, a single-point calibration (e.g., high-low or one-point external standard calibration) is not suitable. In this case, multiple-point external standard calibration is the most appropriate. See Section 3.3.3 for more discussion of the significant y-intercept. 

The single point calibration method assumes that the calibration line goes through the origin. In such a case, precision is increased if the concentration of the reference compound approaches that of the unknown in the sample. It is imperative that instrument tuning does not vary between injections. An excellent reproducibility in the injection volumes is also necessary. 

Classically, quantitation by fluorimetry is done using a calibration curve obtained with reference solutions or by using a single point calibration. In the latter case, the unknown concentration is given by ... 

Single beam, 168 Single point calibration, 77 Size exclusion, 102... 

Single-point calibrations and zero determinations are performed whenever instruments are shut down and/or relocated to a different sampling location. Should the recalibration vary by more than 10% of the value obtained during the initial calibration, the analyzer is recalibrated until stable calibration data are obtained. 

A single point calibration may be used instead of a working calibration curve for quantitation by either external or internal standard method, if the response from the single point standards produces a response that deviates from the sample extract response by no more than 20%. The solvent for preparing calibration standards should preferably be the same one used to make the final sample extract. Hexane, isooctane, or methyl-feri-butylether is an appropriate solvent for the analysis of chlorinated pesticides by GC-ECD. 

According to the number of standards used, the calibration procedures can be subdivided into Single-point calibration Two-point calibration Multi-point calibration. 

For single-point calibration using one standard, the calibration function is assumed to be a straight line defined by the intercept and the theoretical slope factor of the cell. In order to obtain the overall uncertainty of measurement, uncertainties of the respective pH(PS) or pH(SS) values must be taken into account. 

The method employed to evaluate the stability is to use a freshly prepared gas mixture as the calibration gas, and, by means of single-point calibration or linear regression method, determine the Xi (mole fraction of component i) at certain intervals. Then we can figure out the variation factor( expressed in RSD). If the variation factor is within a specific limit, the PRMs are proved stable. 

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